GENEVA, July 5 (Xinhua) -- The UN High Commissioner for Refugees Filippo Grandi on Thursday said he is "gravely concerned" about the civilians caught in the crossfire in southwestern Syria, including airstrikes and heavy shelling.

Grandi said in a statement issued Thursday that an estimated 750,000 people are in danger, and more than 320,000 people are displaced with most of them living in dire and insecure conditions.

"Although local communities in Syria have opened their doors to take in many of the displaced, most are forced to live in open spaces or in makeshift shelters that offer little safety and protection from the elements," he said.

According to the UN refugee head, there are a large number of women and children among the displaced, as well as elderly, injured and sick people.

"Clearly, the most immediate priority is to find a political solution to the conflict and spare Syrian civilians further suffering," he stressed.

He called on all parties to redouble efforts to cease hostilities, to allow humanitarian actors to deliver life-saving assistance and to evacuate the wounded.